期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：17
页码：6684-6688
DOI：10.1073/pnas.87.17.6684
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Most virulence (vir) genes of Agrobacterium tumefaciens that are required for the formation of crown gall tumors are expressed in response to such plant signal molecules as acetosyringone and lignin precursors. The phenolic signals are transduced through a receptor VirA protein in the inner membrane of the bacterial cell. The expression of these genes triggers the transfer of a specific DNA segment, called transferred DNA (T-DNA), from the Ti plasmid to plant cells, and its integration into their nuclear DNA. We show here that a group of aldoses (L-arabinose, D-xylose, D-lyxose, D-glucose, D-mannose, D-idose, D-galactose, and D-talose) can markedly enhance acetosyringone-dependent expression of vir genes when the concentration of acetosyringone is limited (10 microM) but does not enhance the expression of noninducible genes. Likewise, a 2-deoxy-D-glucose, a nonmetabolized sugar, is also effective. When a deletion was introduced into the virA gene in the region encoding the periplasmic portion of the VirA protein, enhancement by glucose disappeared, but vir expression was induced by acetosyringone in this mutant. These results suggest that these sugars directly enhance a signaling process initiated by phenolic inducers that results in an increase in expression of the vir genes.
